Practically all spheres of human activity from heavy industry to transport and household services are today interested in using compact, productive, and functional drive mechanisms. This is due to the continuous improvement of traditional concepts of power units, which, although improved, do not change the basic structure. The most popular basic systems of this type include an electromagnetic drive, the working mechanism of which is used in large-format equipment, and in small technical devices.
Drive purpose
In almost all target applications, this mechanism acts as the executive body of the system. Another thing is that the nature of the function performed and the degree of its responsibility within the framework of the overall work process can change. For example, in shut-off valves, this actuator is responsible for the current position of the valve. In particular, due to its force, the overlap assumes the position of a normally closed or open state. Such devices are used in different communication systems, which determines the principle of operation and the protective characteristics of the device. In particular, an electromagnetic smoke exhaust drive is included in the infrastructure of the fire safety system, structurally docking with ventilation ducts. The drive housing and its critical working parts must be resistant to high temperatures and harmful contacts with thermally hazardous gases. As for the execution command, the automation usually triggers when fixing signs of smoke. The drive in this case is a technical means of regulating the flow of smoke and burning.
A more complex configuration of the use of electromagnetic actuators takes place in multi-way cranes. This is a kind of collector or distribution system, the complexity of which is to simultaneously control entire groups of functional units. Such systems use an electromagnetic valve actuator with the function of switching flows through the nozzles. The reason for closing or opening the channel can be certain quantities of the working medium (pressure, temperature), flow rate, program settings for time, etc.
Construction and components
The central working element of the drive is the solenoid block, which is formed by a hollow coil and a magnetic core. Electromagnetic communications of this component with other parts are provided by small internal fittings with control pulse valves. In normal condition, the core is supported by a spring with a rod that rests in the saddle. In addition, a typical device of an electromagnetic drive provides for the presence of the so-called manual backup of the working part, which takes on the functions of the mechanism in times of sudden changes or complete absence of voltage. Additional functionality provided by signaling means, auxiliary locking elements, and core position fixators may also be provided. But since one of the advantages of drives of this type is its small size, in order to optimize the developers try to exclude excessive saturation of the structure with secondary devices.
The principle of the mechanism
In both magnetic and electromagnetic power devices, the role of the active medium is played by magnetic flux. For its formation, either a permanent magnet or a similar device is used with the possibility of point-wise connection or disconnection of its activity by changing the electrical signal. The executive body begins to act from the moment the voltage is applied, when current begins to flow along the solenoid circuits. In turn, the core begins to move relative to the cavity of the inductor as the activity of the magnetic field increases. Actually, the principle of operation of the electromagnetic drive just comes down to the conversion of electrical energy into mechanical energy through a magnetic field. And as soon as the voltage drops, the forces of an elastic spring come into play, which returns the core to its place and the valve armature takes its initial normal position. Also, to regulate the individual stages of the transmission of force in complex multi-stage drives, pneumatic or hydraulic drives can additionally be included. In particular, they make possible the primary generation of electricity from alternative energy sources (water, wind, sun), which reduces the cost of the equipment workflow.
Executive actions of the electromagnetic drive
The motion pattern of the drive core and its ability to work as an output power unit determine the features of the actions that the mechanism can perform. It should be noted right away that in most cases these are devices with the same elementary movements of the executive mechanics, which are rarely supplemented by auxiliary technical functions. On this basis, the electromagnetic drive is divided into the following types:
- Turning. In the process of supplying current, a power element is triggered, which makes a turn. Such mechanisms are used in ball and plug valves, as well as in butterfly valve systems.
- Reversible. In addition to the main action, it is able to provide a change in the direction of the power element. More common in control valves.
- Pushing. This electromagnetic actuator performs a pushing action, which is also used in distribution and shutoff valves.
From the point of view of the structural solution, the power element and the core may well be different parts, which increases the reliability and durability of the device. Another thing is that the optimization principle requires combining several tasks within the functionality of one technical component in order to save space and energy resources.
Electromagnetic fittings
The drive executive bodies can work in different configurations, performing certain actions required to operate a specific working infrastructure. But in any case, just the function of the core or the power element will not be enough to provide a sufficient effect from the point of view of performing the final task with rare exceptions. In most cases, a transitional link is also required - a kind of translator of generated mechanical energy from directly driven mechanics to the target device. For example, in an all-wheel drive system, an electromagnetic clutch is not just a force transmitter, but an engine that rigidly connects two parts of the shaft. Asynchronous mechanisms even provide their own excitation coil with pronounced poles. The leading part of such couplings is carried out according to the principles of the rotor winding of the electric motor, which completely gives this element the functions of a force transducer and translator.
In simpler systems with direct action, translation tasks are performed by standard ball-bearing devices, articulated and distributing units. The specific execution and configuration of the action, as well as the relationship with the drive system, is implemented in different ways. Often, individual circuits for interfacing components are developed. In the same electromagnetic drive clutch, an entire infrastructure is organized with its own metal shaft, slip rings, manifolds and copper bars. And this is not counting the parallel arrangement of electromagnetic channels with pole tips and contours of the direction of the lines of the magnetic field.
Drive operating parameters
The same design with a typical operation scheme may require the connection of different capacities. Typical models of drive systems also differ in power load, type of current, voltage, etc. The simplest electromagnetic valve actuator operates from a 220 V network, but models with a similar design can also be found, but requiring connection to three-phase industrial networks of 380 V. The power supply requirements are determined by the dimensions of the device and the characteristics of the core. The number of engine revolutions, for example, directly determines the amount of power consumed, and with it the insulation properties, windings and resistance parameters. Speaking specifically about the industrial electrical infrastructure, in the integration project of a powerful drive, the traction forces, the characteristics of the grounding circuit, the implementation scheme of the circuit safety devices must be calculated.
Block drive systems
The most common structural form factor for the release of drive mechanisms on the electromagnetic principle of action is block (or aggregate). This is an independent and partially isolated device, which is mounted on the body of the target mechanism or also a separate executive unit. The fundamental difference between such systems is that their surfaces do not touch the cavities of the transitional power links and, moreover, the working elements of the executive bodies of the target equipment. At the very least, such contacts do not necessitate the adoption of any measures to protect both structures. The block type of electromagnetic drive is used in cases where the functional units need to be isolated from the negative effects of the working environment - for example, from the risks of corrosion damage or temperature effects. To provide a mechanical ligament, the same isolated reinforcing element is used like a rod.
Features of the integrated drive
A kind of electromagnetic power drives, which act as an integral part of the working system, forming with it a single communication infrastructure. As a rule, such devices are compact in size and light in weight, which allows them to be embedded in a wide variety of engineering structures without significantly affecting their functional and ergonomic characteristics. On the other hand, size optimization and the need to expand the possibilities for strapping (direct connection to equipment) limits the creators in providing a high degree of security for such mechanisms. Therefore, typical budget insulating solutions, such as dividing hermetic tubes, helping to protect sensitive elements from the aggressive effects of the working environment, are thought out. Exceptions include vacuum valves with an electromagnetic actuator in a metal case, to which reinforcing units made of high-strength plastic are connected. But these are already specialized enlarged models that have comprehensive protection against toxic, thermal and mechanical factors.
Scopes of the device
Using this drive, the tasks of power mechanical support of different levels are solved. In the most demanding and complex systems for controlling electromagnetic devices, sealless fittings are used to increase the degree of reliability and productivity of equipment. In this combination, the units are used in transport and communication pipeline networks, when servicing storage facilities with petroleum products, in the chemical industry, at processing stations and plants in various industries. If we talk about simple devices, then the electromagnetic drive of the supply and exhaust system fan is common in the domestic sphere. Small-format mechanisms also find their place in plumbing fixtures, pumps, compressors, etc.
Conclusion
With the competent design of the structure of the drive mechanism, based on electromagnetic elements, you can get a pretty profitable source of mechanical effort. In the best versions, such devices are characterized by a high technical resource, stability, minimal energy consumption and flexibility in terms of combining with various actuators. As for the characteristic weaknesses, they are manifested in low noise immunity, which is especially expressed in the operation of the electromagnetic drive of the switch on high-voltage power lines with a voltage of 10 kV or more. Such systems, by definition, need special protection against electromagnetic interference. Also, due to the technical and structural complexity caused by the use of an articulated lever mechanism with a pusher and a retaining latch, additional connection of protective electrical devices is required, eliminating the risks of short circuits in the circuits.